Magnesium base alloy



Patented Jan. 13, 1942 MAGNESIUM BASE ALLOY John C. McDonald, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application December 23, 1940, Serial No. 371,380

3 Claims.

The invention relates to magnesium base alloys and more particularly concerns alloys of this nature having a high degree of formability associated with excellent tensile and yield strengths.

over the entire range of composition indicated, I

have found that, in general, a preferred composition range wherein the most desirable combina- Magnesium base alloys are being widely used in 5 tion of properties exists in one containing from the structural arts where a light weight metal is about 2 to 8 per cent of silver, 0.1 to 0.5 per cent highly desirable, such as for use in making castof c rium, and 5 to 10 per cent of thallium. n s. forgings. a d the like. w v the us f The following table lists some of the properties these f in 9 to make Sheet of rolled sheet metal made from my new quatermetal artlcles requlring forming operations, such nary alloy and compares these properties ith as Pendmg and drawmg, has P progressed as those of related alloys. The new alloy shows imt due to the 9. that i f provement in yield and tensile strengths and is f good formablhty or ductmty Permlttmg also shown to possess a sufficient degree of formrelatlvely sharp bends to be made wlthout the t b t d t f article developing external'cracks, usually have 16 a 1 1 o perml 1 s mng 166 e o orming tions. In the table the per cent elongatmn inferior characteristics as regards their tenslle Ppera and yield strengma ls to be regarded as a measure of the ductlllty or It is, accordingly, the principal object of the inmmablhty the vention to provide a magnesium base alloy which Table Nominal compoggm fg fi Annealed Cold rolled magnwlum) gf 'g f Yield Tensile Yield Tensile Ag Ce Tl strengthln strengtl in strengthln strengtl in finches 1bs./sq. in. lbs./sq.m. lbs/sq. in. lbs./sq. 1n

can be made into rolled sheet and the like possess- The properties set forth above under the termv ing a suflicient degree of ductility or formability annealed were obtained by first rolling the at ordinary temperatures to be sharply bent, alloys at atemperature of 550 F. and thereafter drawn or otherwise shaped, while having good annealing them at various temperatures through tensile and yield strengths. a range of from 400 to 800 F. The properties Other objects and advantages will be apparent selected for the table were those of the annealed as the description of the invention proceeds. specimens which exhibited the maximum elonga- My invention resides in the discovery that a tion. The properties set forth under the term magnesium base alloy containing from 0.3 to 10 cold rolled were obtained by subjecting speciper cent of silver, from 0.01 to l per cent of mens of the alloys which hadfirst been hot rolled cerium, and from 1 to 15 per cent of thallium at a temperature of 550 F. to additional rolling possesses the aforementioned properties. The in the cold state. The properties selected for the term magnesium used herein and in the aptable were those of the cold rolled specimens pended claims is intended to include magnesium which showed the greatest tensile and yield containing the ordinary impurities that are found strengths, while having at least a 1 per cent elonin the commercially pure metal, such as traces gation in 2 inches. of iron, copper, nickel, and silicon. While the A comparison of the properties listed in the properties of high yield and tensile strengths astable shows that the combined strength properties of the new alloy show a high degree of improvement over similar properties of related alloys. In addition the new alloy possesses a high degree of formability so as to render it highly adaptable to forming operations.

While the new alloy is most useful in wrought form, such as sheets, due to its formability characteristics, it may also be used for making castings, extruded forms, and the like. It is further pointed out that my new alloy is amenable to solution and precipitation heat treatments, which accordingly modify its properties.

The new alloy may be compounded by any of the methods usually employed for melting and alloying metals with magnesium, such as by adding the alloying ingredients singly or jointly to a bath of molten magnesium which is preferably protected from oxidation by a suitable flux. Cerium may be added to the alloy as such, or in the form of Misch-metal. Magnesium-cerium alloys are commonly made up by employing Misch-metal as a source of cerium. It is sometimes desirable to add more than the theoretical amount of Misch-metal since the alloying efliciency is not always 100 per cent and some loss may be incurred.

It is to be understood that the invention is not limited to the specific compositions herein described, but may take other forms without departing from the scope of the invention.

I claim:

1. A magnesium base alloy containing from about 0.3 to 10 per cent of silver, 0.01 to 1 per cent of cerium, and from 1 to 15 per cent of thallium, the balance being magnesium.

2. A magnesium base alloy containing from about 2 to 8 per cent of silver, 0.1 to 0.5 per cent of cerium, and from 5 to 10 per cent of thallium, the balance being magnesium.

3. A magnesium base alloy containing from 0.3 to 10 per cent of silver, from 0.01 to 1 per cent of cerium, and from 1 to 15 per cent of thallium and characterized by improved tensile strength and yield strength as compared to similar magnesium-silver-thallium alloy devoid of cerium.

JOHN C. MCDONALD. 

